As an electronic device having an electronic component mounted thereon, there has been known a wireless communication device that transmits beacon signals (wireless tags) or a wearable terminal that is usable while being worn on a body. When a rubber material is used in a substrate of the electronic device, an electronic device having bending resistance or stretching resistance may be implemented regardless of the installation position thereof.
In order to improve the stretching property of an electronic device or a board, a rubber material is used in a substrate of the electronic device or the board, and is also used in a wiring pattern on the substrate. As illustrated in FIG. 19, a bonding member 104 is formed on a wiring pattern 103 of a substrate 102 included in a board 101, and the wiring pattern 103 and a terminal 106 of an electronic component 105 are bonded to each other via the bonding member 104. The wiring pattern 103 is formed using a conductive paste of a rubber material. The bonding member 104 is formed using a solder paste or a conductive paste of a rubber material.
The conductive paste used for forming the wiring pattern 103 has poor solder wettability. Therefore, when the bonding member 104 is formed using a solder paste, a bonding failure may occur between the wiring pattern 103 and the terminal 106 of the electronic component 105.
There is affinity in adhesion between conductive pastes. When adhesiveness between the conductive paste used for forming the wiring pattern 103 and the conductive paste used for forming the bonding member 104 is low, a bonding failure may occur between the wiring pattern 103 and the terminal 106 of the electronic component 105. For example, a silicone-based conductive paste has high adhesiveness to a silicone-based conductive paste, but has low adhesiveness to other conductive pastes excluding the silicone-based conductive paste. Therefore, when a silicone-based conductive paste is used to form the wiring pattern 103, the bonding member 104 is formed using a silicone-based conductive paste. Since the wiring pattern 103 and the bonding member 104 are formed in consideration of adhesiveness between the conductive pastes, the choice of the type of the conductive paste is limited, which makes it difficult to improve cost reduction and mass-productivity.
A metal has a better solder wettability than the conductive paste. When a metal is used as a material of the wiring pattern 103, a solder may be used as a material of the bonding member 104. A metal has high adhesiveness to a conductive paste. When a metal is used as a material of the wiring pattern 103, the choice of the type of a conductive paste used for forming the bonding member 104 is expanded. However, a metal has higher rigidity than that of the conductive paste. Thus, when a metal is used as a material of the wiring pattern 103, the bending property (flexibility) of the board 101 may not be maintained,
The followings are reference documents.    [Document 1] Japanese Laid-Open Patent Publication No. 10-117057,    [Document 2] Japanese Laid-Open Patent Publication No. 2003-243788,    [Document 3] Japanese Laid-Open Patent Publication No. 60-214596, and    [Document 4] Japanese Laid-Open Patent Publication No. 59-169157,